Hydraulic pumping jack



Sept. 4, 1951 L. D. ALWARD HYDRAULIC PUMPING JACK Filed Nov. 22, 1948INVENTOR. [away a i/Wa/d Patented Sept. 4, 1951 HYDRAULIC PUMPING J A'GKLeroy D. ,Alward, Albany, Galifi, assignor to The Pelton Water WheelCompany, San'Francisco, Califl, a corporation of California ApplicationNovember 22, 19.48,ESerial-No.,61,419

1 Claim. 1

My invention relates to means for operating a pump disposed at aconsiderable distance from the operating structure and is particularlyconcerned with a pumping jack in which the valves and other controllinginstrumentalities are of a hydraulic nature. A jack of this variety isshown in the co-pending application of Ira Morgan White, ,filed August5, 194l6, Serial No. 688,498, and assigned to the-assignee of thisapplication.

In a hydraulic pumping jack of the mentioned type, the pistonreciprocates within a cylinder under the control of a hydraulicallyactuated valve for govcrningthe flow from a balancing tank through amain pump into the cylinder and in the reverse direction from thecylinder through the pump back to the balancing tank. The events of thepiston stroke, that is, the point in the stroke ,at which the pistonstarts upwardly, and the point in the stroke at which thepiston startsdownwardly, are governed by the uncovering by the piston of ports in.thecylinder so that the momentary cylinder pressure is exerted throughhydraulic conduits ,upon the control valve. In relativelylargeinstallations the cylinder is quite long and the hydraulic conduitsconnecting the cylinder ports with the controlling instrumentality arelikewise relatively long. .In practice, serious difficulty has beenencountered with breakageof the hydraulic control conduits apparentlydue to water hammer or thephenomenon usually so described, that is tosay one or more surges of momentarilyexcessive pressure.

,Itis therefore an object of my invention to provide ahydraulic pumpingjack ,in which the hydraulic control conduits are not subjected todisruptive forces.

:Another object of the invention is to provide a hydraulic pumping jackin which the flow in thehydraulic controlconduits is itself controlledto preclude breakage.

Another object of the invention is in gel leral toimprove hydraulicpumping jacks.

' Afurther object of the'invention is to provide a ,hydraulic pumpingjack of substantially the customary arrangement but in which means areprovidedfor obviating hydraulic tubing failure due to the phenomenon ofwater hammer.

Another object of the invention is to provide a hydraulic pumping jackin which the hydraulic control conduits are maintained substantiallysupplied with control liquidat all times.

Other objects together with the foregoing are attained in the embodimentof ,the inventiondisclosed in thefollowing description and illustratedin the accompanying drawing in which Figure l is a diagram of ahydraulic pumping jack constructed in accordance with my invention, theparts being illustrated largely by conventional symbols and parts of thedevice being shown in cross-section.

Figure 2 is an enlarged detailshowing in its closed position one of thecheck valves utilized in the controlconduits.

In its preferred form, the hydraulic pumping jack of myinventioncomprises a cylinder having an operating piston reciprocabletherein in accordance with the supply of oil to or the withdrawal of oilfrom the-cylinder beneath the piston. The flow of oil to the cylinder iscontrolled by a valve responsive to pressure conditions within thecylinder because it is connected thereto by relativelylongoil conduits.The conduitsare provided adjacent the cylinder with i check valvestopreventoil flow from the conduits back into the cylinder, in oneinstance, or from the cylinder back into the conduits, in anotherinstance, and

in either case to preclude violent or high velocity flow or pressuresurges in the controlling conduits.

The hydraulic pumping ,jack of my invention canbe embodied in numerousdifferent forms and is susceptible to variation in accordance with itsparticular environment. In the form shown in the drawing, it has workedout quite successfully in overcoming previous defects. In this'mechanismthere is provided alack cylinder .6 within which a piston I isreciprocable. The piston is fast on a rodB extending to a pump, notshown. The cylinder 6 is of relatively great length with respect to itsdiameter andin an actual instance is many feet long. It is usuallyinstalled ,in a vertical position so that the piston ,1 receives thepressure fluid on its under side 19. The pressure fluid is customarily aliquid suchasoil contained in atank H of considerable capacity. A bodyI2 of oiloccupies the lower portion thereof, while the upper portion [3contains, as a cushioning means, air under the samepressureas the oil.

In order to transfer oil from the body l2 into the cylinder 6, there isprovided a suitably driven pump I4 controlled by a main valve It. In onepositionof the main valve, the pump is effective to withdraw oil fromthe body [2 through a pipe I! and to discharge itthrough a pipe {8 ,intothe cylinder 6 beneath the piston '1 thereby driving the piston upwardlyin the cylinder 6. In another position of the main valve I 5, the pumpI4 is effective to withdraw oil from the cylinder 6 from beneaththecorrespondingly lowered piston 1 through the pipe I8 and to discharge itthrough the pipe IT back to the body 2 of oil within the tank I Tooperate the main valve so that the piston is reversed in its motion asit reaches the upper portion of the cylinder and again as it reaches thelower portion of the cylinder, there is provided a pilot valve I9 havingtwo extreme positions. When it is in one extreme position, the pilotvalve is effective to move the main valve comparably, and when it is inits other extreme position, the pilot valve is eifective to move themain valve to a corresponding extreme position. By controlling the pilotvalve, the flow of oil to or from the cylinder 6 is controlled.

For this reason there is provided in the cylinder 6 adjacent the upperend thereof and at appropriately spaced intervals a series of ports 2|,22, 23, 24 and 25. These ports and their connections are all alike andhave similar functions. A description of one of them consequentlyapplies to the others. For example, the port 24 is connected by a shortconduit 21 to a relatively long conduit 28 extending from the upper partof the cylinder 6 downwardly thereof to a master control valve 28 at aconvenient location. The conduit 28 normally is of small diameter but ismany feet long. The control valve 29 is effective to connect the conduit28 or any one of the other conduits, such as the conduit 3|, forexample, to a manifold 32 for communication with a pipe 33 then servingas a continuation of the particular conduit connected. The otherconduits, such as 3|, are isolated when the conduit 28, for example, isconnected. In other words, any one of the conduits can be connected tothe pipe 33 to the exclusion of the remaining conduits to render thecorresponding port in the cylinder wall solely eifective.

Whenever the piston l rises above the selected effective port 24, theatmospheric pressure above the piston previously imposed upon theconduit 21 is quickly replaced by a super-atmospheric pressure, that is,the discharge pressure of the pump hi, a pressure great enough to liftthe piston I and its attendant load. This relatively high pressure iscommunicated through the conduit 21 and the conduit 28 and also thevalve 28 to the manifold 32 from whence it is transmitted to the pipe33. From this pipe the pressure is exerted through a check valve 34 andis carried through a duct 36 to the pilot valve 9.

' The increase in pressure on the pilot valve I9 causes it to change itsposition and correspondingly to actuate the main valve so that thedirection of working fluid flow is reversed. The pump then extractsliquid from the cylinder 6 beneath the piston and the piston descends.As it lowers, it re-covers and passes the port 24 again to expose thatport to the atmospheric pressure above the piston. The high pressureliquid in the conduit 28 quickly drops to atmospheric pressureconcurrently with a partial emptying of the liquid from the conduit 28.Upon a subsequent cycle, when the piston again rises and again subjectsthe relatively long conduit to relatively high pressure, replacementliquid rushes in and a pressure surge is likely to occur. This pressuresurge or water hammer at best is hard on the machinery and is anannoying phenomenon. At worst it is severe enough actually to disruptthe conduit 28, a failure which stops theoperation of the pumping jack.

In accordance with my invention, I provide means for precluding thewater hammer or pressure surge in the conduit 28 due to subjection ofthe port 24 to alternating or varying operating pressures or other surgeproducing conditions. In the conduit 28 at a position closely adjacentthe port 24, there is installed a check valve generally designated 4|and illustrated in detail in Figure 2. The check valve comprises a body42 screwed into the conduit connector 21. Adapted to rest upon a valveseat 43 is a valve bobbin 44 having passageways 46 therein permittingflow through the valve body when the valve is oir' its seat. Flowthrough the body is blocked when the valve is seated. While pressuredifference alone is normally sufiicient to actuate the valve, I providein addition a spring 47 urging the bobbin toward closed position. Whenthe valve is installed in a substantially vertical position as shown inFigures 1 and 2, the spring holds the bobbin closed against the actionof gravity. Suitable fittings 48 facilitate the connection of the checkvalve in the conduit and permit adjustment of the spring.

Since the conduit connector 21 between the cylinder 6 and the valve seat43 is purposely made extremely short, any pressure surges there in areof such minor nature as to be negligible. The conduit 28 and itsappurtenances are subject to relatively high pressure when the pistonuncoversthe port 24 as the valve 4| is forced open in response to thepressure increase. But when the pressure at the port 24 drops to a lowvalue, the valve 4| immediately shuts in response to the pressure changeso that the conduit 28 is not partially emptied into the cylinder 6, andthere is no substantial drop in pressure therein due to such back flow.A subsequent cycle simply reopens the valve'when the high pressurereoccurs and does not set up water hammer or pressure surges as theconduit remains filled with liquid. By the provision of a check valve 4|in each of the conduits connected with the various ports, the active oneis relieved of pressure surges which might interfere with operations andall of the lines are protected from the likelihood of rupture or failuredue to surges.

The pressure which is exerted through conduit 28, for example, andthrough the valve 34 on the pilot valve I9 is reduced in an orderlyfashion or at a non-surge rate as the piston 1 approaches the bottompart of its stroke. For this purpose the cylinder 6 is also providedwith a number of ports 5|, 52 and 53, any one of which may be madeeffective, the others being held ineffective by any suitable removableblocks, not shown. For example, the port 53 freely communicates with acheck valve 54 opening into the cylinder and not otherwise. All of thevalves 54, 56 and 51 are joined to a common line 58 leading through acheck valve 59 into the line 36,

When the piston is above the active one of the ports 5 52 and 53, theassociated check valve is subjected to the pump discharge pressure andhence is closed. When the piston 1 travels below the active port 53, asshown by the dotted lines near the lower end of the cylinder 6 in Figure1, the port 53 is then subjected to atmospheric pressure, and the checkvalve 54 opens a predetermined amount to afford a restricted outlet. Thehigher or pump pressure already in the con duit 28 and in the lines 33,36 and 58 falls at a controlled rate as the contained liquid flowsthrough the port 53 into the space above the piston. In this way thepressure fluctuations and flow velocities in the control conduits andlines 1 are maintained at relatively low values so that disruptiveforces do not occur. The changes in pressure, however, are rapid enoughto be promptly effective upon the pilot valve l9 so that it reverses themain valve when the piston is near the bottom of its stroke and so thatthe cycle of operation is appropriately repeated.

In a hydraulic pumping jack of the sort wherein hydraulic force isutilized to actuate the valves and wherein the size of the cylinder isso great that the hydraulic conduits such as 28 are extremely long andare otherwise subject to surge, the provision in the combination ofcheck valves, such as 4|, adjacent the port 24 leading into the cylinderis in practice effective to avoid any difficulty from pressure surgesand tube failure, and leaves the cycle of operation of the hydraulicmechanism unimpaired and in fact improved.

I claim:

A hydraulic pumping jack comprising a cylinder, a piston reciprocablctherein, means for supplying oil to and withdrawing oil from one end ofsaid cylinder, a valve for controlling said supplying and withdrawingmeans, a relatively long oil conduit extending from said cylinderadjacent said one end to said valve for controlling said valve inaccordance with the position of said piston in said cylinder adjacentsaid one end thereof, a first checl; valve in said conduit adjacent saidcylinder for preventing oil flow from said cylinder into said conduit, asecond check valve in said conduit adjacent said valve for pre ventingoil flow from said conduit into said valve, a second relatively long oilconduit extending from said cylinder adjacent the other end thereof tosaid valve for controlling said valve in accordance with the position ofsaid piston in said cylin der adjacent said other end thereof, a thirdcheck valve in said second conduit adjacent said cylin der forpreventing oil flow from said second conduit into said cylinder, and afourth check valve in said second conduit adjacent said valve forpreventing oil flow from said valve into said second conduit.

LEROY D. ALWARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,185,448 Suter Jan. 2, 19402,287,709 Ringman June 23, 1942 2,470,252 Kyle May 17, 1949 2,481,623Rued Sept. 13, 1949 2,490,323 P unds Dec. 6, 194

